Saturday, January 10, 2015

Under the big sky

NEVILLE HAWCOCK

Yes, I know you can get an app for it. You just hold the tablet up to the sky and it tells you what all the stars are. But I’m not an appy man. I prefer to bag stars with a Collins Gem Guide to the Night Sky and a torch to illuminate the pages. Stare at page; find pattern in sky; memorise. I’ve mastered the northern constellations that way. Now it’s time for another go at the southern.

The last time I went in search of the southern hemisphere skies was an ill-scheduled trip to New Zealand. On the few nights when the clouds parted, the moon’s glare drowned out all but the brightest stars. Still, Canopus and Alpha Centauri, second and third brightest in the sky and never visible from Europe, were moonproof. So was the Southern Cross, totem of the south (it’s on Australia’s flag).

This time I have come to the Atacama Desert in Chile to see if I can do better. The moon and I have synched our calendars and agreed not to overlap. It’s a long way to travel — I live in London — but it’s what a lot of professional astronomers do: they love a lack of atmosphere, and northern Chile has exceptionally thin, dry, clear air, and little light pollution.

Because of this, the region has, in the past couple of decades, become home to some of the world’s biggest telescopes: they include the Very Large Telescope, comprising four instruments with 8.2 metre mirrors, and the still-under-construction European Extremely Large Telescope, with a 39m mirror. (I love the blunt hyperbole of these names: there was to have been a 100m-wide Overwhelmingly Large Telescope but it has been cancelled.)

The latest addition is Alma, the Atacama Large Millimetre/Submillimetre Array. This mighty radio observatory, which comprises 66 antennas, sits 5,000m above sea level on a plateau near the Bolivian border and has cost astronomical organisations in Europe, North America and east Asia $1.4bn to build. It is also conveniently near where I am staying at the Tierra Atacama hotel in the oasis town of San Pedro de Atacama. Alma plans to open its doors to tourists in early 2015, and I have been invited for a preview. For a life-long astro-geek, it’s an irresistible opportunity.

But just as thrilling is the chance to see these skies for myself. So, on my first night at the Tierra, fortified by a pisco sour and armed with Collins Gem and flashlight, I head out for a look — past the little walled pits where crackling log braziers entice guests to sit outside, past the turquoise-lit pool, out along the timber-slat walkway that leads into the grounds at the back. Where it seems darkest, I set my stuff down and get gazing.

As my eyes adapt, the old saw about being careful what we wish for springs to mind: the stars are so rich and clear that the patterns become swamped in detail. But I quickly distinguish Orion lying on his side — has he been on the pisco too? — with brilliant Canopus to the right. High up, there’s Fomalhaut, brightest star of the Southern Fish, which I last saw a few weeks ago skimming the murky glow of south London’s horizon. Best of all I can see the Magellanic Clouds. Looking like two little puffs of vapour, they are, in fact, satellite galaxies of the Milky Way.

This is my idea of fun — I could gaze all night — but eventually the desert chill becomes too much. Near midnight, I pad past the pool and the now-cooling braziers, back to my room. The Tierra is a high-end, low-rise operation, its rooms airy, sparsely, but not cheaply, furnished concrete boxes that do not even have televisions. It could have been designed by an order of modernist monks with a taste for underfloor heating. Less is more; more restful, certainly. Star-sated and cosily warming, I slide into sleep.

The next day I go exploring. The hotel lays on a trip to the Valley of the Moon, a jagged landscape of dunes, cliffs and canyons, scorching under a blue sky. The palette, the default for the Atacama, is beige and grey, with patches of salt here and there like white mould. As my little group passes through a narrow canyon, we can hear resonant little clicks coming from the overhang as the rocks expand in the heat.

For lunch, I stop off in San Pedro, a town where tourism has grown significantly in the past decade. Chile is pushing hard to attract more visitors, and dark, clear skies are part of its USP. The adobe-walled main street has a lot of shopfronts promoting the same excursions, including “Tours Astronómicos”. Still, no one hassles me for custom and the mood is relaxed. After a plate of llama — rather dry but tender — and chips, and a glass of Carmenere, so am I.

At night there’s another trip, to a little observatory. Actually “trip” is overstating it; the dome is right by the hotel, so the minibus seems de trop. But the telescope is worth the visit: with a 16in mirror, it’s big by amateur standards, if Underwhelmingly Small by comparison with its professional counterparts. Once the guide has positioned it, we all take turns — hesitantly in the dark — to peer through the eyepiece: at a bright star, a double star, the Orion nebula, a tight-packed star cluster like a luminous splat of celestial ink. We finish with the Sculptor galaxy, 100bn stars whose light, which set off 11m years ago, has attenuated to a long smear of mist in the lens.

. . .

Alma, the next morning, really is a trip. First we drive for half an hour or so along the geometrically straight highway that runs through the rocky flatland east from San Pedro, towards the Bolivian border; then we turn off and pause at the gatehouse for a site-safety video; then, on a dirt road perpendicular to the highway, we drive for a dozen kilometres or so towards the line of mountains in which the observatory sits. As we steadily ascend, to the left I can see Licancabur, an ominous-looking cone that draws the eye for miles around. Licancabur is dormant but the less obtrusive Lascar to the right puffs out a plume of white vapour, raked sideways by the morning breeze.

The Milky Way, visible in the night sky

Just under 3,000m up, we reach Alma’s Operations Support Facility (OSF), a mini industrial estate where most of the astronomers and support staff work. At its heart are a couple of two-storey buildings, glaringly white and new, with big slatted metal awnings to temper the sun; lizards scamper in the semi-shade. Inside there are offices and kitchens, laboratories and engineering facilities, all very clean and spacious and blessedly air-conditioned. And ordinary: the three astronomers I see tapping away at their PCs could be mulling haulage routes rather than colliding galaxies.

Outside stand two of Alma’s antennas, sturdy white structures bearing burnished metal dishes that are 12m across. Each costs $10m and is designed to receive signals with a wavelength of a millimetre or just below; visible light, to which our eyes are sensitive and which conventional telescopes are designed to gather, has a much shorter wavelength. But astronomers like the millimetre/submillimetre part of the spectrum because it is emitted by interesting things — distant galaxies, embryonic planetary systems — and is not blocked by all the dust that clogs space. (It is heavily absorbed by water vapour, though, hence the appeal of the Atacama, with its puny rainfall.)

Most of the antennas sit at the Array Operations Site (AOS), on the Chajnantor plateau 2,000m higher up; the two here have been brought down for maintenance by Alma’s transporters, two huge 28-wheeled vehicles, in construction-industry yellow, that can lift and carry the 100-ton instruments. The beauty of the plateau is that there’s room to place the antennas in different configurations, up to 15km apart, for different types of observation.

The drawback of the plateau is the risk of altitude sickness. When Alma opens to tourists, with 40 at a time being bussed over for two-hour tours each weekend from San Pedro, the AOS will be off limits. But the OSF is not a bad consolation prize. There will be guided visits round the main building, plus any antennas or transporters that happen to be down from the heights, as well as the usual display boards and videos. The view is tremendous, too: pure Zen desert all the way to the horizon.

I’m granted a peek at the AOS but it’s a palaver to get up there: disclaimer; health check; and, before, during and after the ascent — along a winding gravel road in a chunky pick-up — monitoring of the oxygen in my blood, via a fingertip device. Thais Mandiola, the visitor co-ordinator who drives me there, has to keep in touch with security by radio to assure them all is well.

It’s such a strange landscape that it’s hard to be sure the thin air isn’t getting to me. We pass through a belt of columnar cacti, each two or three metres tall, scattered across the hillside — a forest for minimalists. We spot a pair of vicuna, grazing on desiccated tufts of grass. By the top, I’ve never been anywhere so lifeless: no plants or animals, just gravelly hills and ridges around a dusty plain.

And radio telescopes: a colony of 50 or more gleaming brilliant white in the hard light, with a couple of outliers in the distance. They’re a beautiful sight. It’s like the best sculpture park ever. Or a preview of a Mars colony: ultra-high technology nestled in a dead landscape.

The Tierra Atacama Hotel

Again, there’s an odd mix of the routine and the tech-sublime. As we drive over for a closer look at the dishes, the car radio’s tuned into an easy listening station — hey, it’s “A Kind of Hush” by the Carpenters; then, as I step carefully out and crunch through the gravel towards the antennas, there’s a hum of electric motors and five or six of the huge machines smoothly realign their dishes — tuning in, it might well be, to signals broadcast before the sun was born.

I could happily wander around this exotic zone for hours but health and safety come first. Mandiola drives down gingerly, telling me about speed checks on the dirt track; drivers, it seems, are apt to speed as oxygen floods back into them.

Back at the Tierra Atacama, I refresh myself with a swim. What the pool lacks in size it makes up for in the dragonflies that dart and hover over its surface. When I haul myself out, I look for Alma: it’s not an easy spot but, eventually, I pick out the OSF, just visible on the line of hills. It strikes me that in two days I’ve zoomed through a mini-history of astronomy: from naked eye outside, to telescope in dome, to high-tech antennas funnelling data to computers. I’m glad I came south again.